Measuring greenhouse gases is critical for companies and governments looking to reduce their greenhouse gas emissions. The Greenhouse Gas Protocol (GHGP), created by WRI and The World Business Council on Sustainable Development, is becoming the global standard for measuring GHG emissions. The Swiss-based International Organization for standardization (ISO), the world’s leading developer of standards for corporate accountability, recently adopted the GHG Protocol. Various ISO standards are being used by more than half a million organizations in 159 countries. Standardization will promote a convergence of greenhouse accounting practices globally, and in this way will reduce costs, improve comparability, and strengthen the capacity of corporate leaders to make informed decisions on greenhouse gas risks and opportunities.